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The GMO Potato
Fighting Hunger With the GMO Potato: The "Protato" Goals for GMO Potatoes A staple part of the diet around the world, the potato is consumed daily by around 1 billion peopleChakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533. . The importance of the potato in the diet of the world's population was officially recognized by the United Nation's Declaration of 2008 as, "The International Year of the Potato."United Nations, General Assembly, 2005, "International Year of the Potato, 2008" http://www.un.org/ga/search/view_doc.asp?symbol=A/RES/60/191 The potato has been the focus of several efforts to alter key elements of it's genome in order to increase growing and transport efficiency, increase yield and increase nutrient content. Attempts, with varying degrees of success, have been made to genetically engineer potatoes to be resistant to fungus and reduce bruising caused by transport. There have been many permits issued in the United States and as of today, there have been limited spread of genetically engineered potatoes in US or European food markets. The primary use of genetically potatoes has been for non-human consumption such as animal feeds and various industrial purposes. Perhaps the most promising effects of engineering the potato will happen in the developing world, where many believe that there is a clear need for a nutritious and dependable agricultural productChakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533.. Genetically modifying the potato to increase it's protein content and retain it's ability to grow in many outdoor environments has been achieved. This potato may be successfully introduced into areas where protein and other nutrient deficiencies are widespread problemsChakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533.. What were the original goals of the workers responsible for generating these genetic modifications? ''' Recognizing that a protein-deficient diet is the primary cause of morbidity and mortality in some areas of developing countries, and that potatoes are such a wide-spread staple crop, a group of researchers in India set out to develop a potato that has a significantly increased protein concentration. The health effects of a low-protein diet can include decreased resistance to disease and delays of physical growth and cognitive development. In severe cases of lasting childhood malnutrition, there is strong evidence of permanent cognitive impairmentChakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533.. This research group sought to modify potatoes to increase or add the expression of a protein that had a amino acid content that would meet or exceed World Health Organization guidelines for nutritionally rich protein diet. This requirement is based primarily on the presence of the 6 essential amino acids: arginine, cysteine, glycine, glutamine, proline and tyrosine. Ideally, the protein would be derived from an edible plant, so as to confer safety and optimal taste. Additionally, the researchers sought to modify several existing commercial varieties of potatoes that are grown in different environmental regions, with the aim to develop a global solution to hunger and malnutrition http://www.un.org/ga/search/view_doc.asp?symbol=A/RES/60/191Chakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533.. There have been several attempts to find an appropriate protein and to develop a genetically engineered crop that met all of these specifications. Previous attempts at genetic modifications of various crops including potatoes, rice, soy and various seeds have included the transgenic expression of the Brazil nut 2S albumin in 1989, Amaranth Albumin (AmA1) in 1992, β-phaseoline, HS-7 zein and cruciferin in 1995, and sunflower seed albumin and S-rich zein in 1997. The only transgenic protein that did not disrupt or reduce the endogenous amino acid production was AmA1. Amino acid imbalances in transgenic crops has various problems including structural weaknesses and poor taste. The researchers chose to trans-genetically modify an array of different commercially available potato varieties with the AmA1 protein geneChakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533.. '''Were those goals accomplished in part or in full? The researchers were successfully able to trans-genetically modify 7 commercially available potato varieties with the Amaranth Albumin (AmA1) protein. The Ama1 is found in the seeds of the Amaranth plant, a perennial whose seeds have been harvested and turned into meal since ancient times (See figure 2). The amino acid composition of of AmA1 is rich in essential amino acids, and an great candidate to complement the endogenous amino acid content of wild-type potatoesSupplmentary Materials from Chakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., Nati /14/1006265107.DCSupplemental/pnas.201006265SI.pdf#nameddest=STXT. The researchers field-tested the potatoes for several seasons, and found that not only did the modified potatoes produce 60% more protein than the wild-type, they were also significantly larger. Additionally, in order to assess for any toxicity of the transgenic potatoes, researchers fed rats a diet of either entirely wild-type or the Ama1-transgenic potatoes for 90 days. Health was monitored and several rats were killed and Hemotoxylin and Eosin (H&E) stains of key digestive tissues were assessed for inflammation or damage. No differences were observed between the two test groups in terms of health detriment (Figure 3). Now the question is how wide-spread these "protatoes" will be grown in the developing world and to what degree these crops will improve global nutrition and reduce the negative effects associated with nutrient deficienciesChakraborty S et al., 2010, Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber., National Academy of Science USA, http://www.pnas.org/content/107/41/17533.. Method of Modification: genetic engineering methods or selective breeding The research group used a transformation construct mediated by Agrobacterium tumefaciens (See figure 4). The Ama1 gene was isolated from a cDNA transcript created from Amaranth seeds and inserted into Agrobacterium tumefaciens along with a granule-bound starch synthase (GBSS) promoter and a kanamycin-resistance gene. Successful insertion of the Ama1 gene construct into early potato shoots of each variety was identified by growing the shoots in a kanamycin medium. The successful transgenic shoots were verified using Real-Time PCR for the Ama1 gene. 12 to 24 transgenic shoots of each variety were grown in the greenhouses. These transgenic tubers were then field-tested in various environmental conditions for several years. Total and specific protein content was analyzed in the wild type and transgenic potatoes after each growth cycle. Immunohistochemical techniques showed that Ama1 was localized to the cytoplasm, demonstrating that the transgenic line had the correct desired phenotype. Citations